In the field of chemistry, noble gases are known as essential components in a variety of chemical processes that may have useful application. For example, noble gases are advantageously employed in the operation of a variety of analytical instruments for the purpose of performing one or more chemical reactions that are important to a particular analytical process. The accuracy, if not the success, of such processes is often dependent upon the purity of the noble gas that is supplied to the instrument.
One example of an analytical instrument includes a discharge ionization detector, which operates by applying a high voltage across a set of electrodes that are located in a discharge chamber filled with a discharge gas typically selected from the group of gases known as noble gases. In the presence of a noble gas such as helium, a characteristic discharge emission of photons occurs in the vicinity of the electrodes. The photons irradiate a port connecting the discharge chamber to an ionization chamber that receives a sample gas that typically contains an analyte of interest. Electrons are produced in the ionization chamber as a result of photon interaction with ionizable molecules in the sample gas. Helium metastables are also generated in the vicinity of the discharge emission and are typically transferred from the discharge chamber to the ionization chamber for ionization of the analyte. The magnitude of the ionized analyte molecules is manifested as a current that can be measured to ascertain the composition of one or more components in the analyte.
However, contaminants in the discharge gas are known to degrade the sensitivity of the discharge ionization detector. It is thought that the presence of such ionized contaminants will quench the generation of the helium metastables. As a result, the minimum detectable level (MDL), and the dynamic range, of the detector is degraded.
Accordingly, there exists a need in the field of process chemistry for a system for purification of the discharge gas such that contaminants are reduced if not eliminated.
Further, although the design of discharge ionization detectors continues to be an object of study in the prior art, there nonetheless exists a particular need for a discharge ionization detector having a detector response that exhibits an improved dynamic range, lower minimum detectable level, and greater signal to noise ratio.